Predicting shrinkage deformation of high-strength concrete

Journal of Advanced Concrete Technology, 2016

An extensive research was undertaken in order to determine the dependence of shrinkage of high and normal strength concrete on the compressive strength and concrete composition. The part of research concerning dependence of autogenous shrinkage on compressive strength is presented in this paper. Ten groups of concrete, with the total of twenty nine mixtures, were prepared. Concrete mixtures of each individual group were made using the same quantity of water, while the quantity of cement (CEM II/A-S 42,5R) and mineral admixture (silica fume) was varied in each group. Concrete groups differed according to the quantity of water. Autogenous shrinkage of concrete was monitored together with the influence of initial curing in water on concrete shrinkage. Initial autogenous expansion was noticed during testing autogenous shrinkage, especially on normal strength concrete. Based on the analysis of experimental results, the dependence of autogenous shrinkage at one day of concrete age on compressive strength was defined. The dependence of autogenous shrinkage at later ages on compressive strength of concrete was also presented. Finally, the autogenous shrinkage components of best-known theoretical shrinkage prediction models were compared with experimental data.

Advances in Materials Science and Engineering, 2017

The paper deals with the experimental determination of shrinkage development during concrete ageing. Three concrete mixtures were made. They differed in the amount of cement in the fresh mixture, 300, 350, and 400 kg/m3. In order to determine the influence of plasticiser on the progress of volume changes, another three concrete mixtures were prepared with plasticiser in the amount of 0.25% by cement mass. Measurements were performed with the goal of observing the influence of cement and plasticiser content on the overall development of volume changes in the concrete. Changes in length and mass losses of the concrete during ageing were measured simultaneously. The continuous measurement of concrete mass losses caused by drying of the specimen’s surface proved useful during the interpretation of results obtained from the concrete shrinkage measurement. During the first 24 hours of ageing, all the concrete mixtures exhibited swelling. Its magnitude and progress were influenced by cemen...

https://iopscience.iop.org/article/10.1088/1757-899X/518/2/022077, 2018

Recent trends in concrete technology have been towards high-strength concrete and ultra-high strength concrete with a low water-cement ratio. However, these high and ultra-high strength concretes have some problems. One of the problems is early-age cracking due to autogenous shrinkage. This study presents the results of an experimental investigation carried out to evaluate the autogenous shrinkage of high and ultra-high strength concrete. Main ideas on autogenous shrinkage are based on the use of ordinary Portland cement, but it has already become apparent that mineral admixtures and fibers change the behavior significantly. Variables were taken to study its effect on shrinkage like (effects of water/cement ratio, cement content, coarse aggregate content, silica fume percentage and steel fiber). From the test results, it is concluded that the autogenous shrinkage strain of mixes increases with decrease w/c ratio and decrease with increasing w/c ratio and concrete with the higher value of cement content, shows greater amounts of shrinkage. The autogenous shrinkage strain increases with decreasing of the coarse aggregate content. The additions of 10-20 % of silica fume to the mix increase the autogenous shrinkage strains of concrete specimens. The autogenous shrinkage decreased gradually with the increase of steel fiber content.

2009

 Abstract—This paper presents the results of an experimental investigation carried out to evaluate the shrinkage of High Strength Concrete. High Strength Concrete is made by partially replacement of cement by flyash and silica fume. The shrinkage of High Strength Concrete has been studied using the different types of coarse and fine aggregates i.e. Sandstone and Granite of 12.5 mm

The ASTM C157 free shrinkage test is used to evaluate the effects of mix proportioning parameters and curing on concrete shrinkage with the goal of providing recommendations that will reduce concrete shrinkage in bridge decks. Specimens are dried up to 365 days at 23 ± 2 o C (73 ± 3 o F) and 50 ± 4 percent relative humidity. Parameters include aggregate content; cement fineness; water-cement ratio; curing period; partial cement replacement by slag, Class C fly ash, or silica fume; superplasticizer dosage; the use of a shrinkage reducing admixture; and aggregate type. The results indicate that increasing the aggregate content (decreasing the paste content) of a concrete mix decreases shrinkage and that water-cement ratio has little effect in and of itself. For a given aggregate content and water-cement ratio, concretes made with Type I/II cement shrink more than concretes made with Type II coarse-ground cement. Concrete containing a 30 percent cement replacement (by volume) of either Class C fly ash or granulated ground blast-furnace slag exhibit higher shrinkage than concrete with only Type I/II cement when cured for three days. Limestone coarse aggregate produces concrete with higher shrinkage than concrete made with quartzite coarse aggregate. Increased curing periods lead to a decrease in shrinkage for concretes made with either Type I/II or Type II coarse-ground cement. No consistent effect of dosage rate on shrinkage was observed for concretes made with the superplasticizers tested. The use of a shrinkage reducing admixture at a dosage rate of 2 percent by weight of cement reduced the shrinkage of concrete nearly iv 32 percent after 365 days. The shrinkage reducing admixture, however, produced concrete that at times exhibited an unstable air content.

Advances in Materials Science and Engineering, 2015

The results of a laboratory investigation on the early autogenous shrinkage of high strength concrete, and the possibilities of its reduction, are presented. Such concrete demonstrates significant autogenous shrinkage, which should, however, be limited in the early stages of its development in order to prevent the occurrence of cracks and/or drop in the load-carrying capacity of concrete structures. The following possibilities for reducing autogenous shrinkage were investigated: the use of low-heat cement, a shrinkage-reducing admixture, steel fibres, premoistened polypropylene fibres, and presoaked lightweight aggregate. In the case of the use of presoaked natural lightweight aggregate, with a fraction from 2 to 4 mm, the early autogenous shrinkage of one-day-old high strength concrete decreased by about 90%, with no change to the concrete's compressive strength in comparison with that of the reference concrete.

Civil Engineering Journal

Concrete is indeed one of the most consumed construction materials all over the world. In spite of that, its behavior towards absolute volume change is still faced with uncertainties in terms of chemical and physical reactions at different stages of its life span, starting from the early time of hydration process, which depends on various factors including water/cement ratio, concrete proportioning and surrounding environmental conditions. This interest in understanding and defining the different types of shrinkage and the factors impacting each one is driven by the importance of these volumetric variations in determining the concrete permeability, which ultimately controls its durability. Many studies have shown that the total prevention of concrete from undergoing shrinkage is impractical. However, different practices have been used to control various types of shrinkage in concrete and limit its magnitude. This paper provides a detailed review of the major and latest findings rega...

Automation in Construction, 2015

Shrinkage is a natural phenomenon accompanying drying processes occurring in nature. Particularly acute it is on dirt roads in Africa and Asia, as in the dry season, at high ambient temperatures and low relative humidity, effects of drying are surface irregularities and even landslides. Fresh and hardened concrete mix is subjected to similar phenomena. The mechanism of action of shrinkage in concrete is more complicated than in the environment of cohesive soil, since in the initial phase of hardening chemical processes associated with cement hydration, and after hardening physical processes associated with the adsorption or loss of moisture from the environment during drying, lead to volume reduction. These influences can be precisely separated and indication of their significance for the quality of the concrete structure can be performed only by setting the deformation of concrete in the phase of the laying, caring and operation. The problem of continuous strain measurements in concrete is discussed in this publication, in which a review of existing methods for measuring shrinkage was performed in the period from the start of the modern concrete structures (USA, Europe after 1900 years) to modern times, in which the simple mechanical method of measuring shrinkage was replaced by modern electronic sets of measurement, enabling highly accurate measurements since the moment of production of concrete mix. The exact description of the process of the passing timethe deformation, enables making decisions to rectify or limit unfavourable shrinkage phenomena in the concrete (adding contraction admixtures, water care, covering with foil, use of the sealing and reflecting solar radiation surfaces). Proposed and tested by the authors of the article set-up for automatic control of shrinkage phenomena occurring in the concrete meets the above mentioned functions in both scientific discovery and relevant to practice application research.

Cement and Concrete Research, 2001

This paper presents the results of an experimental study on the influence of curing temperature and type of cement [Portland cement and blast-furnace slag (BFS) cement] on the autogenous deformations and self-induced stresses in early-age concrete. It was found that higher temperatures do not lead to higher deformations in the observed period, but generally cause a faster shrinkage and a faster development of self-induced stresses. Another experimental finding is that, at the temperatures tested, concrete made with BFS cement shows higher shrinkage in the first days than concrete made with Portland cement.

Materials

This paper focuses on the experimental determination of the shrinkage process in Self-Compacting High-Performance Concrete (SCC HPC) exposed to dry air and autogenous conditions. Special molds with dimensions of 100 mm × 60 mm × 1000 mm and 50 mm × 50 mm × 300 mm equipped with one movable head are used for the measurement. The main aim of this study is to compare the shrinkage curves of SCC HPC, which were obtained by using different measurement devices and for specimens of different sizes. In addition, two different times t0 are considered for the data evaluation to investigate the influence of this factor on the absolute value of shrinkage. In the first case, t0 is the time of the start of measurement, in the second case, t0 is the setting time. The early-shrinkage (48 h) is continuously measured using inductive sensors leant against the movable head and with strain gauges embedded inside the test specimen. To monitor the long term shrinkage, the specimens are equipped with specia...